We took my poor boat (H18) over a submerged rock, at speed and shaved about 15cm/6" off one of the dagger boards & broke off some of the trailing edge of the board

The board looks a wee bit sad now. The people who owned the boat before me have obviously patched up the board before and they appear to have used nails in the centre with glass over the top... BAD... the nails have rusted.

I have two questions:

Are there supposed to be any metal/strength members in the board? (ie what's in a factory finished board? Centre core material and some glass derivative outside???)

Any good suggestions for rebuilding the board?

I was thinking of clearing all the crap from the previous owner, off with a grinder and then inserting pins (stainless steel/brass/aluminium?, drill into old structure and then glass them in place ~ 2"), then using resin and grp to build the board back up around the pins and then grind down the board to get the shape back again. Anyone have any experience with doing this in a better/easier manner?

I dunno how applicable this might be to your situation, but you provided me with some good advice in a different post, so maybe you could try building a new one from scratch like my friend and I did with my H16 rudder?

Go to my website, (http://www.JaimeZX.com/Boating) and I have a section in there about building a new rudder. If you have any questions about the process I'd be happy to help, as there are lots of pics I took that are not included in that page.

As we only have a few months when the fjords are not frozen over, repairs have to be done quickly ( okay... bit of an exageration...). We were going to take the boat out in 'Survival' conditions yesterday, but my crew pointed out that it would be survival sailing (wind 36 knots, guests ~ 25% higher), strange... I didn't see the problem. Now he's really good with repairs, took one look at the board and said, stainless steel pins with, glass fibre, car body filler. You can get this amazing filler that has resin mixed with very short strand fibres. So I drilled the pins into the board, glassed them in place and now covered it with the 'miricale patch'. It's sitting in the garage now... hopefully, despite the irritatingly low temperatures it will have cured by tonight and I can see how well it's worked.

The pins were cut to length with an angle grinder and the basic board shape will be drawn on from the other one, the cut with the angle grinder, probably with a stone cutting disk on. Finishing will be sand paper until smooth and then white spray applied longitudinally. Then very fine sanding... Now all the best plans under go revision during operation, but so far this looks like a good plan.

I would try using some type of aluminum stack for this and then some major fiberglassing over that. Theres a new product that lets you mix the epoxy and put it over the mat(the glass itself) like paper and glue. This would best be done with many alternating layers of mat until the desired thickness is reached. then a bandsaw, dremal, and a crap load of sanding should do the trick in shaping the board. Apply the desired type of paint and your good to go. Check out http://www.boatdesigns.com/indexsupplies.html for the epoxy types and mat types.

P.S. Bondo has come out with fiberglass tape that looks like a tensor bandage I haven't tryed it and its pretty expensive(70$US/roll)